JP3298718B2 - Manufacturing method of ultra-thick tempered high strength steel sheet - Google Patents
Manufacturing method of ultra-thick tempered high strength steel sheetInfo
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- JP3298718B2 JP3298718B2 JP26657893A JP26657893A JP3298718B2 JP 3298718 B2 JP3298718 B2 JP 3298718B2 JP 26657893 A JP26657893 A JP 26657893A JP 26657893 A JP26657893 A JP 26657893A JP 3298718 B2 JP3298718 B2 JP 3298718B2
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、均質で優れた強度・靭
性を有する引張強さ１００kgf/mm2 以上、板厚１００mm
超の極厚調質型高強度鋼板の製造方法に関するものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tensile strength of 100 kgf / mm 2 or more and a plate thickness of 100 mm having a uniform and excellent strength and toughness.
The present invention relates to a method for manufacturing a super-thick tempered high-strength steel sheet.
【０００２】[0002]
【従来の技術】溶接構造物の大型化に伴ない鋼材の一層
の高強度化、適用板厚の拡大が進んでいる。既に、橋
梁、ペンストック、海洋構造物では引張強さ８０kgf/mm
2 級の高強度鋼が十分な実績を持つに至っており、引張
強さ１００kgf/mm2 級鋼、しかも、板厚が１００mmを超
える極厚ＨＴ１００鋼が必要とされるようになった。2. Description of the Related Art As the size of a welded structure increases, the strength of steel materials is further increased, and the thickness of applied steel sheets is increasing. Already tensile strength of 80kgf / mm for bridges, penstocks and offshore structures
Second- grade high-strength steels have a sufficient track record, and require a 100-kgf / mm-grade second- grade steel and an extra-thick HT100 steel with a plate thickness exceeding 100 mm.
【０００３】しかし、引張強さ１００kgf/mm2 以上の高
強度鋼を１００mm厚超える極厚で、しかも、安価に安定
して得ることは工業的に容易ではない。However, it is not industrially easy to obtain a high-strength steel having a tensile strength of 100 kgf / mm 2 or more at an extremely thick thickness exceeding 100 mm and at a low cost and stably.
【０００４】極厚調質型高張力鋼板の製造方法として、
例えば、特開平２−１４１５２８号公報はＮｉ３．５超
〜４．５％とやや高価な所定の化学組成とし、成分中の
Ｎｂ添加と二回焼入れによる相乗効果によって、微細な
マルテンサイト組織を得て、極厚のＨＴ１００鋼を得る
方法であるが、これでは、Ｎｉ量と二回熱処理により高
価とならざるを得ない。また、この方法では、低降伏化
のＨＴ１００鋼を得ることはできない。[0004] As a method of manufacturing an extremely thick tempered high strength steel sheet,
For example, Japanese Unexamined Patent Publication (Kokai) No. 2-141528 discloses that a predetermined chemical composition having a slightly expensive Ni content of more than 3.5% to 4.5% is obtained, and a fine martensitic structure is obtained by a synergistic effect of Nb addition and twice quenching. This is a method of obtaining an extremely thick HT100 steel, but in this case, it is inevitably expensive due to the amount of Ni and the heat treatment twice. Further, with this method, it is not possible to obtain a low yielding HT100 steel.
【０００５】[0005]
【発明が解決しようとする課題】１００mm厚を超える極
厚ＨＴ１００鋼を製造するに当たって、強度と靭性を確
保するためには合金添加を大量に行ない、特に、Ｎｉを
多量に添加することで製造可能であるが、これでは、安
価で、且つ、溶接性の良いＨＴ１００鋼を安定して供給
することは難しく、これを解決する安価で安定した極厚
ＨＴ１００鋼の製造法が必要である。In producing an extremely thick HT100 steel exceeding 100 mm in thickness, a large amount of alloy is added in order to secure strength and toughness, and in particular, it can be produced by adding a large amount of Ni. However, in this case, it is difficult to stably supply an inexpensive HT100 steel with good weldability, and a method of manufacturing an inexpensive and stable ultra-thick HT100 steel that solves this is required.
【０００６】[0006]
【課題を解決するための手段】本発明者等は引張強さ１
００kgf/mm2 以上、板厚１００mm超の極厚高張力鋼板の
安価で安定な製造方法につき研究した結果、１００kg
f/mm2 の引張強さを得るためには、金属組織を板厚全体
にわたって細粒マルテンサイト組織とすること、そのた
めに焼入れγ粒を細粒としなければならないのは当然で
あるが、この焼入れ前に細粒γとするためには、Ｎｂ添
加と焼入れ前昇温時の６００℃〜Ａｃ1点で３０分以上
の保持を組合せることにより、加熱γ粒の細粒化が可能
である、また、Ｎｂ添加と焼入れ前昇温時の６００℃
〜Ａｃ1 点で３０分以上の保持を組合せることにより、
上記項の細粒γ粒が得られるのみならず、焼入れ性が
向上し、一回の焼入れ熱処理で十分である。Ｎｉや他の
合金の減少と合せて、安価で溶接性の良好な鋼板の安定
製造が可能である、との知見を見い出した。なお、降伏
化を低減するために二相域熱処理を施こす場合も、その
前の焼入れ熱処理は一回で良い。Means for Solving the Problems The present inventors have a tensile strength of 1%.
As a result of research on an inexpensive and stable manufacturing method of extra-high-tensile-strength steel sheets with a thickness of 100 kgf / mm 2 or more and a thickness of more than 100 mm, 100 kgf / mm 2
To obtain a tensile strength of f / mm 2, it is a fine-grained martensitic structure metallographic throughout the sheet thickness, but its not need the hardening γ grains and granules for is natural, this In order to obtain fine grains γ before quenching, it is possible to make the heated γ grains finer by combining the addition of Nb and holding at one point of 600 ° C. to Ac at the time of temperature rise before quenching for 30 minutes or more. 600 ° C. at the time of temperature increase before Nb addition and quenching
~ Ac By combining holding for more than 30 minutes at one point,
Not only the fine γ grains of the above item can be obtained, but also the hardenability is improved, and one hardening heat treatment is sufficient. In addition to the reduction in Ni and other alloys, it has been found that stable production of a steel plate that is inexpensive and has good weldability is possible. In the case where the two-phase heat treatment is performed to reduce the yield, the quenching heat treatment may be performed only once.
【０００７】本発明は、上記知見に基づきなされたもの
であり、その要旨とするところは次の通りである。 （１）重量％で、Ｃ：０．１０〜０．２０％、Ｓｉ：
０．０５〜０．５０％、Ｍｎ：０．５０〜１．５０％、
Ｃｕ：０．０４〜１．５０％、Ｎｉ：２．５〜４．０
％、Ｃｒ：０．０４〜１．５０％、Ｍｏ：０．０４〜
１．０％、Ｎｂ：０．００５〜０．０４％、Ａｌ：０．
０３〜０．１％、Ｂ：０．０００３〜０．００５％、
Ｎ：０．００４％以下、Ｐ：０．０１％以下、Ｓ：０．
０１％以下を基本成分とし、残部がＦｅおよび不可避不
純物からなる鋼を、１１００℃以上に加熱して熱間圧延
した後、再加熱焼入れするに際し、６００℃〜Ａｃ1 点
の間で３０分以上保持してＡｃ3 点〜１０００℃の温度
域に加熱して焼入れを行ない、続いてＡｃ1 点以下の温
度で焼戻して水冷することを特徴とする板厚１００mm超
の極厚調質型高強度鋼板の製造方法。[0007] The present invention has been made based on the above findings, and the gist thereof is as follows. (1) In weight%, C: 0.10 to 0.20%, Si:
0.05 to 0.50%, Mn: 0.50 to 1.50%,
Cu: 0.04 to 1.50%, Ni: 2.5 to 4.0
%, Cr: 0.04 to 1.50%, Mo: 0.04 to
1.0%, Nb: 0.005 to 0.04%, Al: 0.
03-0.1%, B: 0.0003-0.005%,
N: 0.004% or less, P: 0.01% or less, S: 0.
After hot-rolling a steel containing not more than 01% as a basic component and the balance consisting of Fe and unavoidable impurities to 1100 ° C. or more, and then reheating and quenching, it is 30 minutes or more between 600 ° C. and one point of Ac. Extra strength tempered mold with a thickness of more than 100 mm, characterized in that it is held and heated to a temperature range of Ac 3 points to 1000 ° C. to perform quenching, followed by tempering at a temperature of Ac 1 point or less and water cooling. Steel plate manufacturing method.
【０００８】（２）さらに、Ｖ：０．１％以下、Ｔａ：
０．０５％以下からなる強度向上元素群のうちの１種ま
たは２種を含むことを特徴とする（１）記載の極厚調質
型高強度鋼板の製造方法。 （３）さらに、Ｔｉ：０．１％以下、Ｃａ：０．０００
５〜０．００６０％の低温靭性向上・均質化元素群のう
ちの１種または２種を含むことを特徴とする（１）記載
の極厚調質型高強度鋼板の製造方法。 （４）さらに、Ｖ：０．１％以下、Ｔａ：０．０５％以
下からなる強度向上元素群のうちの１種または２種と、
Ｔｉ：０．１％以下、Ｃａ：０．０００５〜０．００６
０％の低温靭性向上・均質化元素群のうちの１種または
２種を含むことを特徴とする（１）記載の極厚調質型高
強度鋼板の製造方法。(2) Further, V: 0.1% or less, Ta:
(1) The method for producing a high-thickness tempered high-strength steel sheet according to (1), wherein one or two of a group of strength improving elements consisting of 0.05% or less are included. (3) Further, Ti: 0.1% or less, Ca: 0.000
(1) The method for producing an ultra-thick tempered high-strength steel sheet according to (1), comprising one or two members of a low-temperature toughness improving / homogenizing element group of 5 to 0.0060%. (4) One or two of a group of strength improving elements consisting of V: 0.1% or less and Ta: 0.05% or less;
Ti: 0.1% or less, Ca: 0.0005 to 0.006
(1) The method for producing a high-strength tempered high-strength steel sheet according to (1), comprising one or two members of a low-temperature toughness improving / homogenizing element group of 0%.
【０００９】（５）焼入れと焼戻しの間で、Ａｃ1 点超
〜Ａｃ3 点未満の間に加熱して急冷する二相域熱処理を
施こすことを特徴とする（１）記載の極厚調質型高強度
鋼板の製造方法。 （６）焼入れと焼戻しの間で、Ａｃ1 点超〜Ａｃ3 点未
満の間に加熱して急冷する二相域熱処理を施こすことを
特徴とする（２）記載の極厚調質型高強度鋼板の製造方
法。 （７）焼入れと焼戻しの間で、Ａｃ1 点超〜Ａｃ3 点未
満の間に加熱して急冷する二相域熱処理を施こすことを
特徴とする（３）記載の極厚調質型高強度鋼板の製造方
法。 （８）焼入れと焼戻しの間で、Ａｃ1 点超〜Ａｃ3 点未
満の間に加熱して急冷する二相域熱処理を施こすことを
特徴とする（４）記載の極厚調質型高強度鋼板の製造方
法。 これによって１００mm超の極厚ＨＴ１００鋼および低降
伏比を有する極厚ＨＴ１００鋼が、安価に安定して製造
可能とすることができる。(5) Between the quenching and the tempering, a two-phase region heat treatment of heating and rapidly cooling between more than Ac 1 point and less than Ac 3 points is performed. Method of manufacturing high quality high strength steel sheet. (6) Between the quenching and the tempering, a two-phase region heat treatment of heating and rapidly cooling between more than Ac 1 point and less than Ac 3 points is applied. Manufacturing method of high strength steel sheet. (7) Between the quenching and the tempering, a two-phase region heat treatment of heating and rapidly cooling between more than Ac 1 point and less than Ac 3 points is applied. Manufacturing method of high strength steel sheet. (8) Between the quenching and the tempering, a two-phase zone heat treatment of heating and rapidly cooling between more than Ac 1 point and less than Ac 3 points is applied. Manufacturing method of high strength steel sheet. Thereby, it is possible to stably manufacture an extremely thick HT100 steel having a thickness of more than 100 mm and an extremely thick HT100 steel having a low yield ratio at low cost.
【００１０】[0010]
【作用】以下、本発明を作用と共に詳細に説明する。先
ず、鋼成分を上記のように限定した理由を述べる。Ｃは
鋼板の強度を確保するために必要であり、その含有量が
０．１０％未満では１００kgf/mm2 の強度を満たすこと
はできず、一方、０．２０％を超えると溶接低温割れ性
が高くなることから、０．１０〜０．２０％に限定す
る。Ｓｉは製鋼上脱酸元素として必要であり、また、強
度確保のために０．０５％以上必要であるが、０．５０
％を超えると、溶接性および溶接熱影響部（ＨＡＺ）靭
性が低下するため、０．０５〜０．５０％に限定する。
Ｍｎは焼入れを向上させ、強度・靭性を確保するために
０．５０％以上必要であるが、１．５０％を超えて含有
させると、靭性低下を招き、また、ＨＡＺの硬化を生
じ、溶接性を損なうので、０．５０〜１．５０％に限定
する。Hereinafter, the present invention will be described in detail together with the operation. First, the reasons for limiting the steel components as described above will be described. C is necessary to secure the strength of the steel sheet. If the content is less than 0.10%, the strength of 100 kgf / mm 2 cannot be satisfied. Is increased, the content is limited to 0.10 to 0.20%. Si is required as a deoxidizing element on steel making, and is required to be 0.05% or more for securing strength.
%, The weldability and the weld heat affected zone (HAZ) toughness decrease, so the content is limited to 0.05 to 0.50%.
Mn is required to be 0.50% or more in order to improve quenching and secure strength and toughness. However, if Mn is contained in excess of 1.50%, the toughness is reduced, and the HAZ is hardened. Therefore, the content is limited to 0.50 to 1.50%.
【００１１】Ｃｕは焼入れ性や強度を上げるのに有用な
元素であり、その効果を奏すのに０．０４％以上必要で
あるが、一方、１．５０％を超えて含有させても、コス
トアップに見合う強度上昇効果が見られないので、０．
０４〜１．５０％に限定した。Ｎｉは焼入れ性向上効果
と靭性向上効果を有するが、その含有量が２．５％以下
では、１００mm超板厚で１００kgf/mm2 以上の高強度を
確保することができず、一方、４．０％を超えて添加し
てもコストアップに見合う効果が得られず、徒らに高価
になるだけのため、２．５〜４．０％に限定した。Ｃｒ
は焼入れ性や強度を上げるのに有用で、この効果を得る
のに０．０４％以上必要であるが、一方、１．５０％を
超えると、溶接性、靭性を低下させる故、これを上限と
する。[0011] Cu is an element useful for increasing the hardenability and strength, and is required to be 0.04% or more in order to exhibit its effects. There is no strength increase effect commensurate with the up, so
Limited to 04-1.50%. 3. Ni has a hardenability improving effect and a toughness improving effect, but if its content is 2.5% or less, high strength of 100 kgf / mm 2 or more cannot be ensured with a sheet thickness of more than 100 mm. Even if it is added in excess of 0%, an effect commensurate with cost increase cannot be obtained, and the cost becomes unnecessarily high. Therefore, the content is limited to 2.5 to 4.0%. Cr
Is useful for increasing the hardenability and strength, and 0.04% or more is required to obtain this effect. On the other hand, if it exceeds 1.50%, the weldability and toughness are reduced, so the upper limit is set. And
【００１２】Ｍｏは焼入れ性や強度を上げると共に、焼
戻し脆性を防止するのに有用であり、その効果を得るの
に０．０４％以上必要であるが、一方、１．０％を超え
ると、ＨＡＺを著しく硬化させ、溶接性、靭性を低下さ
せるので、これを上限とする。Mo is useful for improving hardenability and strength and preventing temper embrittlement, and it is necessary to obtain 0.04% or more to obtain the effect. Since the HAZ is remarkably hardened and the weldability and toughness are reduced, this is set as the upper limit.
【００１３】Ｎｂは炭窒化物を生成し、γ粒を細粒化さ
せる効果を持つが、その効果を得るのに０．００５％以
上必要である。一方、０．０４％を超えると、溶接性を
損なうことから、これを上限とする。Ａｌは細粒化を図
り、且つ、焼入れ性に有効なＢを得るのに必要で、その
効果を奏するには０．０３％以上必要であるが、０．１
％を超えた添加はアルミナ系介在物の増加を招き、鋼板
の清浄度・靭性を損なうので、０．０３〜０．１％に限
定する。Nb forms carbonitrides and has the effect of making γ grains finer, but at least 0.005% is required to achieve this effect. On the other hand, if it exceeds 0.04%, the weldability is impaired, so this is made the upper limit. Al is required to reduce the grain size and to obtain B effective for hardenability. To achieve the effect, 0.03% or more is required.
%, The addition of alumina-based inclusions causes an increase in alumina-based inclusions and impairs the cleanliness and toughness of the steel sheet.
【００１４】Ｂは鋼の焼入れ性を向上するのに必須の元
素であり、０．０００３％以上必要であるが、０．００
５％を超える添加はＢ系介在物を多くし、靭性を損なう
ので、０．０００３〜０．００５％に限定する。ＮはＡ
ｌやＮｂと結びついて、窒化物を生成し、γ粒の細粒化
に有効であるが、０．００４％を超えると、固溶Ｎが多
くなり、溶接部の靭性を低下させるので、これを上限と
する。ＰとＳは共に低くすることにより、靭性を向上す
る効果を持つが、その効果を得るのに、両元素共、０．
０１％以下とする必要がある。B is an essential element for improving the hardenability of steel, and is required to be 0.0003% or more.
Addition of more than 5% increases the amount of B-based inclusions and impairs toughness, so the content is limited to 0.0003 to 0.005%. N is A
In combination with l and Nb, nitrides are formed and are effective in refining γ grains. However, when the content exceeds 0.004%, solid solution N increases and the toughness of the welded portion is reduced. Is the upper limit. By lowering both P and S, there is an effect of improving the toughness.
It is necessary to be less than 01%.
【００１５】本発明では、上記必須基本成分の他に、要
求される鋼の特性に応じて、以下の元素を１種または２
種選択的に含有させることができる。ＶとＴａは、鋼の
強度を向上させるという均等的作用を持つもので、必要
に応じて１種または２種含有させるが、それぞれＶ：
０．１％、Ｔａ：０．０５％の上限を超えて含有させて
も、溶接性を阻害し、且つ、高価になり過ぎる悪影響が
出るため、上記強度向上元素のそれぞれ成分上限を定め
る。In the present invention, in addition to the above essential basic components, one or more of the following elements may be used depending on the required properties of the steel.
It can be contained selectively. V and Ta have an equivalent effect of improving the strength of the steel, and one or two of them are contained as necessary.
Even if the content exceeds the upper limit of 0.1% and Ta: 0.05%, the weldability is impaired and the cost becomes too high, so that the upper limit of each component of the strength improving element is set.
【００１６】また、ＴｉとＣａは、鋼の低温靭性を向上
するという均等的作用を持つもので、必要に応じて１種
または２種含有させるが、それぞれＴｉ：０．１％、Ｃ
ａ：０．００６０％の上限を超えて含有させても、いた
ずらに高価となり、且つ、溶接性や均質性を阻害する。
また、Ｃａはその作用を発揮するのに０．０００５％以
上が必要である。このことから、上記靭性向上・均質元
素群のそれぞれの上限および下限を定める。Further, Ti and Ca have an equivalent effect of improving the low-temperature toughness of the steel, and one or two of them may be contained as necessary.
a: Even if the content exceeds the upper limit of 0.0060%, it is unnecessarily expensive and also impairs weldability and homogeneity.
Ca must be 0.0005% or more to exhibit its effect. From this, the upper limit and the lower limit of each of the toughness improving / homogeneous element group are determined.
【００１７】次に、本発明鋼の熱処理法につき述べる。
上記のような鋼成分に加え、高強度鋼としての良好な特
性を得るためには、熱処理法が適切でなければならな
い。ここで熱処理条件の限定理由につき説明する。先
ず、スラブの加熱は合金元素や析出元素の十分な固溶を
図るため、１１００℃以上に加熱することが必要で、こ
れを下限として熱間圧延を行なう。圧延後、焼入れ熱処
理のための加熱を行なうが、この昇温時６００℃〜Ａｃ
1点の間で３０分以上の保持を行なう。本発明成分のＮ
ｂ添加鋼をこの温度範囲で保持することにより、微細で
十分な炭窒化物を得ることができ、その後の焼入れ時に
細粒γ粒を得ることができる。６００℃未満では、この
効果が十分得られない。また、Ａｃ1 点超では、微細な
炭窒化物のγへの固溶が生じ、期待の効果が得られな
い。それ故、６００℃〜Ａｃ1 点に限定する。Next, the heat treatment method of the steel of the present invention will be described.
In order to obtain good properties as a high-strength steel in addition to the above steel components, a heat treatment method must be appropriate. Here, the reasons for limiting the heat treatment conditions will be described. First, the slab must be heated to 1100 ° C. or higher in order to achieve a sufficient solid solution of the alloying element and the precipitation element. After rolling, heating for quenching heat treatment is performed.
Hold for more than 30 minutes between one point. N of the component of the present invention
By maintaining the b-added steel in this temperature range, fine and sufficient carbonitrides can be obtained, and fine γ grains can be obtained during subsequent quenching. If the temperature is lower than 600 ° C., this effect cannot be sufficiently obtained. On the other hand, if the Ac point exceeds 1 , the fine carbonitride forms a solid solution in γ, and the expected effect cannot be obtained. Therefore, it is limited to 600 ° C. to one Ac point.
【００１８】次に、熱処理法はいわゆる焼入れ、焼戻し
を施こす。但し、降伏比を低くしたＨＴ１００鋼を製造
する場合は焼入れと焼戻しの間に二相域熱処理を施こ
す。十分な焼入れ性を確保するために、Ａｃ3 点以上へ
の加熱を行なうが、１０００℃を超えるとγ粒の粗大化
が生じるため、焼入れ温度はＡｃ3 点〜１０００℃に限
定した。焼戻し処理は、焼入れ組織からの析出強化元素
の十分な析出を図るためであると同時に、焼入れ組織の
回復・軟化を行ない、靭性を得るためである。Ａｃ1 点
を超えた温度では強度・靭性が著しく低下するので、Ａ
ｃ1 点を上限とする。また、焼戻し後の冷却速度が遅い
と焼戻し脆性により靭性の低下を生じるため、水冷とす
る。二相域熱処理は前述のように降伏比を下げるために
行なうが、Ａｃ1点以下およびＡｃ3 点以上では二相域
処理にならず、降伏比を下げることができないので、下
限をＡｃ1 点超、上限をＡｃ3 点未満とする。二相域か
らの冷却は、焼入れ性を確保するため、急冷とする。Next, in the heat treatment method, so-called quenching and tempering are performed. However, when producing HT100 steel with a low yield ratio, a two-phase region heat treatment is performed between quenching and tempering. To ensure sufficient hardenability, it performs the heating of the Ac 3 point or more, to produce exceeds the γ grains coarsen 1000 ° C., the quenching temperature is limited to Ac 3 point to 1000 ° C.. The tempering treatment is for achieving sufficient precipitation of the precipitation strengthening element from the quenched structure, and at the same time, for recovering and softening the quenched structure and obtaining toughness. If the temperature exceeds the Ac 1 point, the strength and toughness significantly decrease.
c One point is the upper limit. Further, if the cooling rate after tempering is low, the toughness is reduced due to tempering embrittlement. Two-phase region a heat treatment is performed to lower the yield ratio as described above, but not in the two-phase region treatment at least one point or less and Ac 3 point Ac, it is not possible to lower the yield ratio, the lower limit Ac 1 point Exceed, the upper limit is less than Ac 3 points. Cooling from the two-phase region is quenched to ensure hardenability.
【００１９】[0019]
【実施例】表１に示す成分組成のスラブを製造し、これ
らを表２に示す条件にて圧延・熱処理を施こし、板厚１
５０mmの極厚鋼板を製造した。その後、得られた各鋼板
から試験片を切り出し、機械的性質と溶接性の評価を行
ない、その結果を表２に併せて示した。溶接性の評価は
ｙ型溶接割れ試験方法により、各鋼板より採取した板厚
５０mm試験片を１５０℃に予熱後入熱１７kJ／cmの標準
溶接条件にて溶接し、その後、表面割れ、ルート割れお
よび断面割れの有無を調べた。EXAMPLE A slab having the composition shown in Table 1 was manufactured and subjected to rolling and heat treatment under the conditions shown in Table 2 to obtain a slab having a thickness of 1%.
An extremely thick steel plate of 50 mm was manufactured. Thereafter, a test piece was cut out from each of the obtained steel sheets, and mechanical properties and weldability were evaluated. The results are shown in Table 2. The weldability was evaluated by the y-type welding crack test method by welding a 50 mm thick test piece from each steel plate under standard welding conditions of a heat input of 17 kJ / cm after preheating to 150 ° C, and then surface and root cracks. And the presence or absence of a section crack was examined.
【表１】 [Table 1]
【００２０】[0020]
【表２】 [Table 2]
【００２１】[0021]
【表３】 [Table 3]
【００２２】[0022]
【表４】 [Table 4]
【００２３】[0023]
【表５】 [Table 5]
【００２４】[0024]
【表６】 [Table 6]
【００２５】表２の結果から明らかなように、本発明で
規定する条件通りに製造された極厚鋼板は引張強度１０
０kgf/mm2 以上で、靭性も表面から板厚中心まで良好
で、且つ溶接割れ性も良好であることが分かる。また、
試験番号９から１４では低降伏比鋼板が得られている。As is clear from the results shown in Table 2, the extremely thick steel plate manufactured under the conditions specified in the present invention has a tensile strength of 10%.
It can be seen that at 0 kgf / mm 2 or more, the toughness is good from the surface to the center of the sheet thickness, and the weld cracking property is also good. Also,
In Test Nos. 9 to 14, low yield ratio steel sheets were obtained.
【００２６】しかし、発明鋼と同成分であっても、製造
方法が本発明の規定から外れると、良好な性能を得るこ
とができない。また、比較鋼の場合に、特に、溶接割れ
性が不良となる。例えば、試験番号１５と１９では６０
０℃−Ａｃ1 点昇温時間が短く靭性が不良である。試験
番号１６は加熱温度が低く、試験番号１７は焼入れ温度
が低く、いずれも強度、特に１／２ｔ部の強度１００kg
f/mm2 未満と低い。試験番号１８は焼戻し後水冷を行な
っておらず低温靭性が不良である。試験番号２０は焼戻
し温度が高過ぎ靭性が不良である。さらに試験番号２
１，２２，２３は成分が発明範囲を超えており、溶性割
れ性が不良である。However, even with the same components as the inventive steel, good performance cannot be obtained if the production method deviates from the provisions of the present invention. Further, in the case of the comparative steel, particularly, the weld cracking property becomes poor. For example, in test numbers 15 and 19, 60
0 ° C.-Ac One- point heating time is short and the toughness is poor. Test No. 16 has a low heating temperature, and Test No. 17 has a low quenching temperature.
f / mm 2 and less than low. In Test No. 18, water cooling was not performed after tempering, and the low-temperature toughness was poor. In Test No. 20, the tempering temperature was too high and the toughness was poor. Test number 2
1,2,23 have components exceeding the range of the invention and have poor solubility cracking properties.
【００２７】[0027]
【発明の効果】この発明によれば、板厚１００mm超、引
張強さ１００kgf/mm2 以上で靭性および溶接性の良好な
極厚高強度鋼板および低降伏比の極厚高強度鋼板を安価
に安定して製造することが可能となり、産業上極めて有
用な効果がもたらされる。According to the present invention, an ultra-thick high-strength steel sheet having a thickness of more than 100 mm and a tensile strength of 100 kgf / mm 2 or more and having good toughness and weldability and an ultra-thick high-strength steel sheet having a low yield ratio can be manufactured at low cost. It can be manufactured stably, and an industrially extremely useful effect is brought about.
フロントページの続き (56)参考文献 特開 昭60−21326（ＪＰ，Ａ) 特開 昭61−223125（ＪＰ，Ａ) 特開 昭62−202020（ＪＰ，Ａ) 特開 昭62−235421（ＪＰ，Ａ) 特開 平５−186820（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C21D 8/00 - 8/10 C22C 38/00 - 38/60 Continuation of the front page (56) References JP-A-60-21326 (JP, A) JP-A-61-223125 (JP, A) JP-A-62-202020 (JP, A) JP-A-62-235421 (JP) , A) JP-A-5-186820 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) C21D 8/00-8/10 C22C 38/00-38/60
Claims (8)
る鋼を、１１００℃以上に加熱して熱間圧延した後、再
加熱焼入れするに際し、６００℃〜Ａｃ1 点の間で３０
分以上保持してＡｃ3 点〜１０００℃の温度域に加熱し
て焼入れを行ない、続いてＡｃ1 点以下の温度で焼戻し
て水冷することを特徴とする板厚１００mm超の極厚調質
型高強度鋼板の製造方法。1. C .: 0.10 to 0.20% by weight, Si: 0.05 to 0.50%, Mn: 0.50 to 1.50%, Cu: 0.04 to 1.50 by weight% %, Ni: 2.5 to 4.0%, Cr: 0.04 to 1.50%, Mo: 0.04 to 1.0%, Nb: 0.005 to 0.04%, Al: 0. B: 0.0003% to 0.005%, N: 0.004% or less, P: 0.01% or less, S: 0.01% or less, with the balance being Fe and After hot rolling the steel consisting of unavoidable impurities to 1100 ° C. or more, when reheating and quenching, 30 ° C. between 600 ° C. and one point of Ac.
Extra-thickness temper with a thickness of more than 100 mm, characterized in that it is quenched by heating to a temperature range of Ac 3 points to 1000 ° C. while holding for more than 1 minute, and then tempered at a temperature of Ac 1 point or less and water-cooled. Manufacturing method of high strength steel sheet.
下からなる強度向上元素群のうちの１種または２種類を
含むことを特徴とする請求項１記載の極厚調質型高強度
鋼板の製造方法。2. The extra-thickness refining according to claim 1, wherein one or two of a group of strength improving elements consisting of V: 0.1% or less and Ta: 0.05% or less are included. Method for manufacturing high-strength steel sheets.
５〜０．００６０％の低温靭性向上・均質化元素群のう
ちの１種または２種を含むことを特徴とする請求項１記
載の極厚調質型高強度鋼板の製造方法。3. Ti: 0.1% or less, Ca: 0.000
The method for producing a high-strength tempered high-strength steel sheet according to claim 1, comprising one or two of a low-temperature toughness improving / homogenizing element group of 5 to 0.0060%.
下からなる強度向上元素群のうちの１種または２種と、
Ｔｉ：０．１％以下、Ｃａ：０．０００５〜０．００６
０％の低温靭性向上・均質化元素群のうちの１種または
２種を含むことを特徴とする請求項１記載の極厚調質型
高強度鋼板の製造方法。4. One or two of a group of strength improving elements consisting of V: 0.1% or less and Ta: 0.05% or less;
Ti: 0.1% or less, Ca: 0.0005 to 0.006
The method for producing an ultra-thick tempered high-strength steel sheet according to claim 1, wherein the method includes one or two of a low-temperature toughness improving / homogenizing element group of 0%.
ｃ3 点未満の間に加熱して急冷する二相域熱処理を施こ
すことを特徴とする請求項１記載の極厚調質型高強度鋼
板の製造方法。5. Between the quenching and the tempering, more than Ac 1 point to A
2. The method for producing a high-strength tempered high-strength steel sheet according to claim 1, wherein a two-phase heat treatment of heating and quenching during less than 3 points is applied.
ｃ3 点未満の間に加熱して急冷する二相域熱処理を施こ
すことを特徴とする請求項２記載の極厚調質型高強度鋼
板の製造方法。6. The method according to claim 1, wherein: between quenching and tempering, more than 1 point of Ac to A
c. The method for producing a high-strength tempered high-strength steel sheet according to claim 2, wherein a heat treatment is performed during less than 3 points to perform a rapid cooling in a two-phase region.
ｃ3 点未満の間に加熱して急冷する二相域熱処理を施こ
すことを特徴とする請求項３記載の極厚調質型高強度鋼
板の製造方法。7. The method according to claim 1, wherein the step of: between the quenching and the tempering, from more than Ac 1 point to A
c. The method for producing a high-strength tempered high-strength steel sheet according to claim 3, wherein a heat treatment is performed in a two-phase region where the temperature is rapidly reduced by heating during less than 3 points.
ｃ3 点未満の間に加熱して急冷する二相域熱処理を施こ
すことを特徴とする請求項４記載の極厚調質型高強度鋼
板の製造方法。8. The method according to claim 1, wherein the temperature between the quenching and the tempering is more than Ac 1 point to A
Thick tempered type high-strength steel sheet manufacturing method of claim 4, wherein the straining facilities the two-phase region heat treatment quenching by heating between c less than 3 points.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26657893A JP3298718B2 (en) | 1993-10-25 | 1993-10-25 | Manufacturing method of ultra-thick tempered high strength steel sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26657893A JP3298718B2 (en) | 1993-10-25 | 1993-10-25 | Manufacturing method of ultra-thick tempered high strength steel sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07118741A JPH07118741A (en) | 1995-05-09 |
| JP3298718B2 true JP3298718B2 (en) | 2002-07-08 |
Family
ID=17432760
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP26657893A Expired - Fee Related JP3298718B2 (en) | 1993-10-25 | 1993-10-25 | Manufacturing method of ultra-thick tempered high strength steel sheet |
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| JP5630321B2 (en) * | 2011-02-24 | 2014-11-26 | Ｊｆｅスチール株式会社 | High-tensile steel plate with excellent toughness and manufacturing method thereof |
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